Axial flow compressor

ABSTRACT

An axial flow compressor is disclosed. The axial flow compressor includes a tapered housing, having a first open end and a second open end forming a fluid channel therebetween; a shaft, disposed axially within the tapered housing from the first open end to the second open end; a plurality of rotors, mounted to the shaft within the tapered housing for compressing air within the tapered housing; and a plurality of stators, mounted within the tapered housing; wherein the plurality of rotors, plurality of stators and tapered housing are not in physical contact.

FIELD OF THE INVENTION

The present invention relates to compressors, and in particular to an axial flow compressor for increasing the power output of an internal combustion engine.

BACKGROUND OF THE INVENTION

Superchargers are devices for increasing the power output of internal combustion engines. They achieve this by increasing the mass of air which is input to the cylinders, thereby increasing the combustible mass of the air-fuel mixture in each cylinder or combustion chamber above that which would be compressed by the piston at atmospheric pressure.

U.S. Pat. No. 6,450,156 is directed towards an air compressor for charging an internal combustion engine includes a compressor for blowing compressed air into the intake manifold of the engine and a gas powered turbine for driving the compressor. In a first embodiment, the exhaust from a small gas powered turbine is coupled to the driving turbine of a standard turbocharger. In a second embodiment, the drive shaft of a small gas powered turbine is coupled to the drive shaft of a standard supercharger. In a third embodiment, a compressor turbine having an air intake, a compressed air outlet, and a bleed air outlet is coupled to a small gas powered turbine such that the bleed air outlet supplies the combustor intake of the gas turbine. The gas powered turbine drives the compressor and receives compressed air from the compressor via the bleed outlet. The system provides a constant boost, does not use engine horsepower, is easy to install, and does not need to be coupled to a rotating shaft or the exhaust system of the engine.

U.S. Patent App. No. 20020157397 is directed towards an exhaust power recovery system for internal combustion engines. The engine exhaust gases drive a gas turbine that in turn drives a hydraulic turbine pump pressurizing a hydraulic fluid which then in turn is the driving source for a hydraulic motor which transmits power to the engine shaft. In a preferred embodiment the engine exhaust gases drive a gas turbine with pivotable stator vanes that in turn drives a hydraulic pump pressurizing hydraulic fluid which than in turn is the driving source for a hydraulic motor which transmits power to the engine shaft. The pivotable stator vanes function as an efficient variable nozzle providing precise gas turbine control and improved exhaust energy utilization over a wide range of engine operating conditions. Various embodiments of the present invention make it applicable to a wide range of engines. For high power density engines such as 20 kW/Liter and higher, the engine supercharging system is configured as a combination of hydraulic supercharger in series with turbocharger, such as in the previous invention. For low power density engines as 20 kW/Liter and lower, the supercharging system is configured with either a hybrid supercharger/turbocharger unit or with a standard commercial turbocharger

U.S. Pat. No. 6,328,024 is directed towards a supercharger employing an axial flow electric compressor or fan with its various connections to an internal combustion engine to obtain more power from the engine. A control system is also described to operate the supercharger from the throttle mechanism to obtain extra power with the use of the supercharger when the engine is otherwise performing at its normal full power.

U.S. Pat. No. 6,751,957 is directed towards an electronically driven pressure boosting system that is used to boost the torque output of an internal combustion engine. The system comprises an electrically driven supercharger, an electrical supply system for providing electrical power to drive the pressure charging device including a battery and an engine-driven battery recharger, a switch to connect and disconnect the battery and recharger and an engine control system for controlling the switch and the operation of the pressure charging device. The engine control system is used to determine a capacity utilization of the electrical supply system, and then to control the switch to isolate at least partially the battery from the engine-driven battery recharger and drive the pressure charging device using the battery when said capacity utilization is above a first threshold.

U.S. Pat. No. 6,718,955 is directed towards a multiple electric motor driven centrifugal air compressor, for example, for gasoline or diesel engine powered vehicles.

U.S. Pat. No. 6,135,098 is directed towards an electric air charger for use with an internal combustion engine is disclosed. The air charger includes an impeller for supplying air to the engine. A housing surrounds the impeller and has an air inlet and an air outlet adapted to couple the air supplied by the impeller to the engine. The air inlet and the air outlet are substantially axially aligned. The air charger further includes an electric motor for controllably rotating the impeller.

U.S. Pat. No. 5,025,629 is directed towards a turbocharger for an internal combustion engine can provide a two-stage compressor with movable stator blades to shift the compressor performance and match the air output of the turbocharger to varying air requirements of an internal combustion engine. The turbocharger can also be provided with a generally optimum boost pressure ratio of about 4.5:1 to 4.6:1. Such a compressor comprises a first axial-compressor stage, typically providing a 1.3:1 pressure boost ratio, and a second radial-compressor stage, typically providing a pressure ratio of 3.5:1. The turbine of such a turbocharger can be a combination flow turbine and can be provided with closure means to vary the turbine geometry and provide more efficient turbine operation at low-engine speeds. The turbocharger includes a roller bearing system adapted to accommodate imbalance. A control system operating in response to engine-operating conditions can operate the compressor-stator vanes and, if present, the turbine closure means.

There is a need, however, for an axial flow compressor that can easily and quickly be mounted to the engine intake of an internal combustion engine and has multiple compression stages for a cascade effect to increase air pressure through the stages. None of the references mentioned above disclose such a device. The present axial flow compressor operates on the principle of acceleration of air followed by diffusion to convert the kinetic energy to a pressure rise.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object of the present invention to provide an axial flow compressor that spools up to maximum speed immediately to provide exceptionally quick response.

It is a further object of the present invention to provide an axial flow compressor that includes a tapered housing, having a first open end and a second open end forming a fluid channel therebetween; a shaft, disposed axially within the tapered housing from the first open end to the second open end; a plurality of rotors, mounted to the axle within the tapered housing for compressing air within the tapered housing; and a plurality of stators, mounted within the tapered housing; wherein the plurality of rotors, plurality of stators and tapered housing are not in physical contact.

In accordance with a first aspect of the present invention, a novel axial flow compressor is provided. The novel axial flow compressor is formed of lightweight materials to allow it to spool up to maximum speed immediately to provide exceptionally quick response.

In accordance with another aspect of the present invention, a novel axial flow compressor is provided. The novel axial flow compressor includes a tapered housing, having a first open end and a second open end forming a fluid channel therebetween; an axle, disposed axially within the tapered housing from the first open end to the second open end; a plurality of rotors, mounted to the axle within the tapered housing for compressing air within the tapered housing; and a plurality of stators, mounted within the tapered housing; wherein the plurality of rotors, plurality of stators and tapered housing are not in physical contact.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description of a preferred embodiment of the present invention will be better understood when read with reference to the appended drawings, wherein:

FIG. 1A is a perspective view, in partial cross section, of the stator vanes in an axial flow compressor in accordance with the present invention.

FIG. 1B is a perspective view of a stator vane in accordance with the present invention.

FIG. 2 is a perspective view of a rotor assembly of the axial flow compressor in accordance with the present invention.

FIG. 3 is a schematic representation of a rotor/stator arrangement of the axial flow compressor demonstrating the cascade effect.

FIG. 4 is a schematic representation of the axial flow compressor in accordance with the present invention and a graphic representation of a pressure ratio in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, wherein like reference numerals refer to the same components across the several views and in particular to FIGS. 1A, 1B, 2, and 3, an axial flow compressor 10 is depicted. The axial flow compressor 10 includes a tapered housing 11, having a first open end 12 and a second open end 13. In operation, air flows into the first open end 12 through the tapered housing 11 and out of the second open end 13.

The tapered housing 11 includes a plurality of rotors 20 within it, which have a plurality of blades 25. A plurality of stators 30 are mounted within the case 11, and are paired with one of the plurality of rotors 20. Each of the plurality of stators 30 include vanes 35. The speed of the plurality of rotors 20 determines the velocity of air present in each stage and with increased velocity, kinetic energy is transferred to the air. The vanes 35 of the plurality of stators 30 are placed between their respective blades 25 of the plurality of rotors 20 and the second open end 13 of the tapered housing 11 to receive the air at high velocity and act as a diffuser, changing kinetic energy to potential energy in the form of pressure. Secondarily, the plurality of stators 30 direct air flow to the next stage of compression at the desired angle.

The plurality of rotors 20 are mounted to a shaft 40, and proceed outward radially from the shaft 40. The shaft 40 is disposed within the tapered housing 11 such that the plurality of rotors 20 are disposed within a plurality of gaps 31 between each stage of rotors 20. In this manner, the shaft 40 can be rotated and the plurality of rotors 20 will rotate within their respective gap 31 compressing air from stage to stage with the plurality of stators 30 from the inlet 12 to the outlet 13.

The blades 35 are reduced in size from the first stage beginning proximate to the first open end 12 of the tapered housing 11 to the last stage mounted proximate to the second open end 13 of the tapered housing 11 to accommodate the taper of the tapered housing 11 that houses them. The blades 35 include a vane shank 37 which is mounted to the interior of the tapered housing 11 and a vane tip 38.

Referring now to FIG. 3, the high pressure zone air of the first stage blade 25 is depicted being pumped into the low pressure zone of its associated stator vane 35. A leading edge 36 of the stator vane 35 faces the opposite direction of its associated rotor blade 25 leading edge 26, thereby causing the pumping action to occur. The high pressure zone of the 1^(st) stage stator vane 35 then pumps into the low pressure zone of the 2^(nd) stage rotor blade 25 (not shown). This cascade progress continues through to the last stage of compression. The shaft 40 rotates in the direction of the arrow R to produce this effect, and the flow of air F proceeds through the inlet vanes 50 to be compressed into the axial flow compressor 10.

FIG. 4 depicts the taper of the tapered housing 11. In general, according to Bernoulli's principle, as pressure builds up in the rear stages of the compressor, velocity tends to drop accordingly. In order to stabilize the velocity the shape of the compressor fluid path converges from the first open end 12 to the second open end 13. This taper allows the amount of space that the compressed air can occupy. The shaft 40 traverses the tapered housing 11 from the first open end 12 to the second open end 13 and has mounted on it the plurality of rotors 20 to rotate the rotors 20. Each set of blades 25 accelerate the air through the tapered housing 11 while the stator vanes 35 increase the pressure of the air through the different stages using the principle of convergent and divergent effect. The vanes 35, in a preferred embodiment of the present invention are capable of variable angles.

In particular, when the air leaves the compressor blades 25, it flows into a row of stator vanes 35. The stator vanes 35 also form diverging ducts which decrease the velocity of the air and increase the static pressure. The compressor blade and stator vane action continues through all the stages of the axial flow compressor 10.

When the air leaves the axial flow compressor 10, it will have approximately the same velocity with which it started, but a much greater static pressure. A particular molecule of air would probably rotate no more than 180° through the axial flow compressor 10 due to the straightening effect. And since the last compression stage followed by a stationery vane set, called exit guide vanes, the airflow is turned completely back to an axial direction on its way to the combustor of the engine.

The axial flow compressor 10 makes use of ram pressure recovery. As the vehicle moves forward a condition known as ram pressure recovery takes place where the pressure inside the first open end 12 returns to ambient value. The engine thereby takes advantage of this process with a corresponding increase in compressor pressure ratio, thus requiring less fuel expenditure to create more power.

As pressure builds in the rear stages of the compressor, velocity tends to drop in accordance with Benoullis Theory. This is not desirable because, in order to create pressure the compressor operates on a principle of velocity change in air flow. In order to stabilize the velocity, the shape of the compressor gas path converges, reducing to approximately 25% to 35% of the inlet flow area, however, any taper known to one of ordinary skill in the art may be employed as the taper. This tapered shape provides the proper amount of space for the compressed air to occupy.

In view of the foregoing disclosure, some advantages of the present invention can be seen. For example, a novel axial flow compressor is provided. The novel axial flow compressor includes rotors and stators that are not in physical contact with one another to limit wear and tear, and are formed of materials light enough to allow for maximum spool up. In this manner, multiple stages are used to provide a cascade effect to increase air pressure through the stages, which is the only use of such an axial flow concept on ground vehicles.

While the preferred embodiment of the present invention has been described and illustrated, modifications may be made by one of ordinary skill in the art without departing from the scope and spirit of the invention as defined in the appended claims. For example, in a preferred embodiment of the present invention, the tapered housing is formed of aluminum, the axle is formed of steel, and the stators and blades are formed of high-density carbon fiber. However, any material know to one of ordinary skill in the art may be employed to form the tapered housing, axle, stators and blades. Additionally, in a preferred embodiment of the present invention, there are four stages to the compressor, however, any number of stages can be employed, known to one of ordinary skill in the art. 

1. An axial flow compressor, comprising: a tapered housing, having a first open end and a second open end forming a fluid channel therebetween; a shaft, capable of rotation, disposed axially within the tapered housing from the first open end to the second open end; a first plurality of rotors, radially mounted to the shaft within the tapered housing for compressing air within the tapered housing; and a first plurality of stators, mounted within the tapered housing; wherein the first plurality of rotors, first plurality of stators and tapered housing are not in physical contact.
 2. The axial flow compressor of claim 1, wherein the first plurality of rotors include blades and the first plurality of stators include vanes.
 3. The axial flow compressor of claim 2, wherein the blades include a leading edge and the vanes include a leading edge.
 4. The axial flow compressor of claim 3, wherein the leading edge of the blades are mounted opposite to the direction of the leading edge of the vanes.
 5. The axial flow compressor of claim 2, wherein the tapered housing is formed of aluminum.
 6. The axial flow compressor of claim 2, wherein the stator vanes are formed of high-density carbon fiber.
 7. The axial flow compressor of claim 2, wherein the rotor blades are formed of high-density carbon fiber.
 8. The axial flow compressor of claim 2, wherein the axle is formed of high speed steel.
 9. The axial flow compressor of claim 1, further comprising a second plurality of rotors and a second plurality of stators.
 10. The axial flow compressor of claim 9, further comprising a third plurality of rotors and a third plurality of stators.
 11. The axial flow compressor of claim 10, further comprising a fourth plurality of rotors and a fourth plurality of stators.
 12. The axial flow compressor of claim 1, wherein the first open end of the tapered housing receives air via ram pressure recovery.
 13. The axial flow compressor of claim 12, wherein the pressure inside the first open end of the tapered housing returns to ambient pressure by means of the ram pressure recovery.
 14. The axial flow compressor of claim 1, wherein the tapered housing tapers to between 25% and 35% from the first open end to the second open end.
 15. The axial flow compressor of claim 14, wherein the tapered housing tapers to 25% from the first open end to the second open end.
 16. The axial flow compressor of claim 14, wherein the tapered housing tapers to 35% from the first open end to the second open end. 